Cosmological Constraint on the Minimal Universal Extra Dimension Model

Cosmological Constraint onCosmological Constraint on the Minimal Universal the Minimal Universal

Extra Dimension Model Extra Dimension Model Mitsuru Kakizaki Mitsuru Kakizaki (Bonn University)(Bonn University)

September 7, 2007 @ KIAS

In collaboration with Shigeki Matsumoto (Tohoku Univ.) Yoshio Sato (Saitama Univ.) Masato Senami (ICRR, Univ. of Tokyo)

Refs: PRD 71 (2005) 123522 [hep-ph/0502059] NPB 735 (2006) 84 [hep-ph/0508283] PRD 74 (2006) 023504 [hep-ph/0605280]

September 7, 2007 Mitsuru Kakizaki 2

1. 1. MotivationMotivation 　　

Non-baryonic dark matterNon-baryonic dark matter[http://map.gsfc.nasa.gov]

Neutralino (LSP) in supersymmetric (SUSY) models 1st KK mode of the B boson (LKP) in universal extra dimension (UED) models etc.

Today’s topic

Observations of cosmic microwave background structure of the universe etc.

Weakly interacting massive particles (WIMPs) are good candidatesThe predicted thermal relic abundance naturally explains the observed dark matter abundance

The predicted thermal relic abundance naturally explains the observed dark matter abundance


OutlineOutline Reevaluation of the relic density of LKPs including both coannihilation and resonance effects Cosmological constraint on the minimal UED model

Reevaluation of the relic density of LKPs including both coannihilation and resonance effects Cosmological constraint on the minimal UED model

1. Motivation2. Universal extra dimension (UED) models3. Relic abundance of KK dark matter4. Coannihilation processes5. Resonance processes6. Summary

c.f.: SUSY

[From Ellis, Olive, Santoso,Spanos, PLB565 (2003) 176]


2. Universal extra 2. Universal extra dimension (UED) models dimension (UED) models

Idea: All SM particles propagate in flat compact spatial extra dimensionsIdea: All SM particles propagate in flat compact spatial extra dimensions

[Appelquist, Cheng, Dobrescu, PRD64 (2001) 035002]

Dispersion relation: Momentum along the extra dimension = Mass in four-dimensional viewpoint

compactification with radius :

Mass spectrum for

quantized

Momentum conservation in the extra dimensionConservation of KK number at each vertex

Macroscopic

MicroscopicMagnify

KK tower


Conservation of KK parityThe lightest KK particle (LKP) is stable

The LKP is a good candidate for dark matterThe LKP is a good candidate for dark matter

c.f. R-parity and LSP

In order to obtain chiral zero-mode fermions, the extra dimension is compactified on an orbifold

Minimal UED Minimal UED (MUED) (MUED) modelmodel

Only two new parameters appear in the MUED model:: Size of extra dimension: Scale at which boundary terms vanish

More fundamentaltheory

The Higgs mass remains a free parameter Constraints coming from electroweak measurements are weak

[Flacke, Hooper, March-Russell, PRD73 (2006); Erratum: PRD74 (2006); Gogoladze, Macesanu, PRD74 (2006)]

[+ (--) for even (odd) ]

for

[Haisch, Weiler, hep-ph/0703064 (2007)]

Precision tests


Mass spectra of KK statesMass spectra of KK states KK particles are degenerate in mass at tree level:

[From Cheng, Matchev, Schmaltz, PRD66 (2002) 036005]

Radiative corrections relax the degeneracy

KK particles of leptons and Higgs bosons are highly degenerate with the LKP

1-loop corrected mass spectrum at the first KK level

Compactification 5D Lor. inv. Orbifolding Trans. Inv. in 5th dim.

Lightest KK Particle (LKP): Degenerate in mass

(mixture of )

Coannihilation plays an important rolein calculating the relic density


3. Relic abundance3. Relic abundance of KK dark matter of KK dark matter

After the annihilation rate dropped below the expansion rate, the number density per comoving volume is almost fixed

Standard thermal scenario

Increasing

Decoupling

Thermal equilibrium

Dark matter particles were in thermal equilibrium in the early universe

[From Servant, Tait, NPB 650 (2003) 391]

Co-moving number density

Relic abundance of the LKP

Inclu

ding

coa

nnih

ilatio

nW

ithou

t coa

nnih

ilatio

n

3 flavors

No resonance process included Coannihilation only with the NLKP

Shortcomings:


4. Coannihilaition processes4. Coannihilaition processes

[From Kong, Matchev, JHEP0601(2006)]

WMAP

Disfavored byEWPT

The relic abundance depends on the SM Higgs mass Resonance effects also shift the allowed mass scale

The relic abundance depends on the SM Higgs mass Resonance effects also shift the allowed mass scale

Relic abundance of the LKP: Inclusion of coannihilation modes with

all 1st KK particles reduces the effective cross section

The Higgs mass is fixed to No resonance process included

Our emphasis:

[Burnell, Kribs, PRD73(2006); Kong, Matchev, JHEP0601(2006)]

With

out c

oann

ihila

tion

Previous calculation:

Shortcomings:


Masses of the KK Higgs Masses of the KK Higgs bosonsbosons

-0.5 %

1st KK Higgs boson masses: Contour plot of the mass splitting of

LargerLarger ; smaller

(Enhancement of the annihilation cross sections for the KK Higgs bosons) Too large The 1st KK charged Higgs boson is the LKP

[Cheng, Matchev, Schmaltz, PRD66 (2002) 036005]


Allowed regionAllowed region without resonance processes without resonance processes

All coannihilation modes with 1st KK particles included

KK Higgs coannihilation region

Bulk region

Bulk region

KK Higgs coannihilation region

(small )

(large )

Our result is consistent with previous works

The relic abundance decreasesthrough the Higgs coannihilation

Larger is allowed


5. Resonance processes5. Resonance processes

(Incident energy of two 1st KK particles)

KK particles were non-relativistic when they decoupled

(Masses of 2nd KK particles) Annihilation cross sections are enhanced through s-channel 2nd KK particle exchange at loop level

Important processes:e.g.


-resonance contributes as large as -resonances

Allowed region including Allowed region including coannihilation and resonance coannihilation and resonance

Including resonances

Without resonances

In the KK Higgs coannihilation region:

In the Bulk region:

-resonances are effective

Cosmologically allowed region is shifted upward by


Remark: KK graviton problemRemark: KK graviton problem For ,

Introduction of right-handed neutrinos of Dirac type [From Matsumoto, Sato, Senami

, Yamanaka, PLB647, 466 (2007)]

LKP in the MUED

KK graviton LKP region

Attempts:

Radion stabilization?

Emitted photons would distort the CMB spectrum

[Feng, Rajaraman, Takayama PRL91 (2003)]

decays at late times

is a DM candidate

[Matsumoto, Sato, Senami, Yamanaka, PRD76 (2007)]

WMAP data can be as low as


Coannihilation

6. Summary6. Summary

UED models contain a candidate particle for CDM: The 1st KK mode of the B boson (LKP)

Cosmologically allowed region in the MUED model

We calculated the LKP relic abundance in the MUED model including the resonance processes in all coannhilation modes

In UED models

Resonance


Backup slidesBackup slides


The LKP relic abundance is dependent on the effective annihilation cross section

Calculation of Calculation of the LKP abundance the LKP abundance

Naïve calculation without coannihilation nor resonance

Coannihilation Resonance

[Servant, Tait, NPB650 (2003) 391]

[Burnell, Kribs, PRD73(2006); Kong, Matchev, JHEP0601(2006)]

[Matsumoto, Senami, PLB633 (2006)]

[MK, Matsumoto, Sato, Senami, PRD71 (2005) 123522; NPB735 (2006) 84; PRD74 (2006) 023504]

[Servant, Tait, NPB650 (2003) 391]

The 1st KK particle of the B boson is assumed to be the LKP

;Coannihilation with KK Higgs bosons for large

Coannihilation with all 1st KK particles

Coannihilation with KK right-handed leptons

;

WMAP data

;


Constraint on Constraint on in the MUED model in the MUED model

Constraints coming from electroweak measurements are weak

[Appelquist, Cheng, Dobrescu PRD64 (2001); Appelquist, Yee, PRD67 (2003); Flacke, Hooper, March-Russell, PRD73 (2006); Erratum: PRD74 (2006); Gogoladze, Macesanu, PRD74 (2006)]

[From Gogoladze, Macesanu, PRD74 (2006)]

Excluded

Allowed

(Under the assumption of thermal production)

Requiring that LKPs account for the CDM abundance in Universe, the parameter space gets more constrained

Requiring that LKPs account for the CDM abundance in Universe, the parameter space gets more constrained


Relic abundance of the LKPRelic abundance of the LKP (without coannihilation) (without coannihilation)

The resonance effect shifts upwards the LKP mass consistent with the WMAP data

The resonance effect shifts upwards the LKP mass consistent with the WMAP data

The --resonance in annihilation effectively reduces the number density of dark matter


KK Higgs coannihilation regionKK Higgs coannihilation region [Matsumoto, Senami, PLB633 (2006)]

Coannihilation effect with 1st KK Higgs bosons efficiently decrease the LKP abundance

Coannihilation effect with 1st KK Higgs bosons efficiently decrease the LKP abundance

LKP relic abundance (ignoring resonance effects)

WMAP

Larger Higgs mass (larger Higgs self-coupling)

Mass degeneracy between 1st KK Higgs bosons and the LKP in MUED

of 1 TeV is compatible with the observation of the abundance

Larger annihilation cross sections for the 1st KK Higgs bosons


KK Higgs coannihilation regionKK Higgs coannihilation region

The effective cross section can increase after freeze-out

Freeze-out

The LKP abundance can sizably decrease even after freeze-out

For larger

[Matsumoto, Senami, PLB633 (2006)]

(larger Higgs self-coupling) Degeneracy between the LKP and

Free from a Boltzmann suppression

Larger


Origin of the shiftOrigin of the shift

Including resonance

Without resonance

KK Higgs coannihilation region

Bulk region

res.

-res.are effective

-res.

-res.contributes as large as


Positron experimentsPositron experiments

The HEAT experiment indicated an excess in the positron flux:

Future experiments (PAMELA, AMS-02, …) will confirm or exclude the positron excess

KK dark matter may explain the excess

Unnatural dark matter substructure is required to match the HEAT data in SUSY models[Hooper, Taylor, Silk, PRD69 (2004)]

[Hooper, Kribs, PRD70 (2004)]


Including coannihilationIncluding coannihilation with 1 with 1stst KK singlet leptons KK singlet leptons

The LKP is nearly degenerate with the 2nd KK singlet leptons

The allowed LKP mass region is lowered due to the coannihilation effect

c.f. SUSY models: coannihilation effect raises the allowed LSP mass

Coannihilation effect is important Annihilation cross sections


Coannihilaition processesCoannihilaition processes KK particles of leptons and Higgs bosons are highly degenerate with the LKP Coannihilation plays an important role

in calculating the relic density

In generic:

e.g.: coannihilation with KK leptons:

e.g.: coannihilation with KK Higgs bosons:

Cosmological Constraint on the Minimal Universal Extra Dimension Model

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